81551402 has 8 divisors (see below), whose sum is σ = 123449700. Its totient is φ = 40401504.

The previous prime is 81551389. The next prime is 81551413. The reversal of 81551402 is 20415518.

It can be written as a sum of positive squares in 2 ways, for example, as 81522841 + 28561 = 9029^2 + 169^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 186827 + ... + 187262.

Almost surely, 2^81551402 is an apocalyptic number.

81551402 is a deficient number, since it is larger than the sum of its proper divisors (41898298).

81551402 is a wasteful number, since it uses less digits than its factorization.

81551402 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 374200.

The product of its (nonzero) digits is 1600, while the sum is 26.

The square root of 81551402 is about 9030.5814873684. The cubic root of 81551402 is about 433.6544532324.

The spelling of 81551402 in words is "eighty-one million, five hundred fifty-one thousand, four hundred two".